Tiompan is right June. I replied to you about it being a red and blue moon on that thread. Eclipse makes the moon turn red every time. Visually. Blue moon has come to mean an extra moon in a month only since 1946. It used to be a belewe moon in 1500's when it was first recorded as a saying, meaning a betrayer moon which was when an extramoon before lent threw the date off. A visibly blue moon happens because of atmospheric dust and gives rise to the once in a blue moon phrase because it is extremely rare. There was dust and a visibly blue moon, as well as an eclipse, which turns it red for the duration of the eclipse, in a month where it just happened to be an extra full moon and called a blue moon by modern standards.